• Smooth muscle tissue- Mesenchyme
• Striated skeletal muscle and striated cardiac muscle -Mesoblast
• Myoepithelial cells (epithelial cells covering the muscle tissue- Ectoblast
• Muscle tissues are classified by innervation and/or striation into:
• Voluntary and involuntary (by innervation)
- Striated skeletal muscle tissue - Voluntary
- Smooth muscle tissue - Involuntary
- Striated cardiac muscle tissue - Involuntary
• Striated and smooth muscles (by striation)
- Striated skeletal and striated cardiac
- Smooth muscle tissue – Visceral (internal organs such as the intestines),
- Myo-epithelial cells in the acini,
- Sphincters and dilatators of the pupils of the eye
Smooth muscle tissue. Structural, ultra-structural, chemical and functional
Origin: Mesenchyme, involuntary
• Cellular type of microscopic
Organization where the nuclei
Are arranged centrally.
• non-striated muscle
• Thin-elongated muscle cells (fibres) pointed at their ends with a single,
Large, oval nucleus.
• Filled with sarcoplasm (specialized cytoplasm) and is surrounded by
Sarcolemma (thin cell membrane).
• Each cell has many myofibrils, which lie parallel to one another.
• Smooth muscle fibres cross over to form layers of muscle tissue rather
Than bundles as in striated.
Function (Hint: Involuntary)
- Located in the walls of hollow organs such as the digestive tract (lower part of
The esophagus, stomach and intestines), the walls of the bladder (cannot control
The urge for urination), the uterus (Childbirth involuntary response),
Various ducts of glands and the walls of blood vessels (contraction and relaxation
Of the vessels move blood along).
- Single-unit variety mostly, either contraction or relaxation of the whole unit
(blood vessels, urinary tract, digestive tract), but there is also multiunit smooth
Muscles (trachea, the large elastic arteries, and the iris of the eye).
- Myosin works together with actin to form a motor unit where actin and myosin
Slide over each other to cause muscle contraction using energy from ATP. Actin
And Myosin take up most of cytoplasmic space.
- Contractions of smooth muscle move food through the digestive tracts and push
Blood through the blood vessels.
- The weakest of all muscle tissues, visceral (smooth) muscle makes organs
Contract to move substances through the organ
Cardiac striated muscle tissue
Origin: Mesoblasts lead to the formation of cardiomyocytes. Involuntary muscle.
• Presence of intercalated discs organised in a step like manner.
• The intercalated discs consist of gap junctions (nexus) and desmosomes.
• This allows the cardiac muscles to stay attached under strain
• Reduces the gap through which nerve impulse passes through thereby speeding
Up the process of stimulation.
• This allows cardiac muscle tissue to contract very quickly in a wave-like
Types: There are 3 types of cardiac muscle tissue: 1. Contractile, 2. Pacemakers 3.
1. Contractile muscle tissue allows the heart to beat as one unit as each muscle cell is
Connected to 4 other contractile cells through intercalated disks (tick plasma
Membrane) as a branch.
2. Pacemakers allow conduction of nerve impulse (sino atrial node and atrial ventricular
Node). Pacemakers have fewer myofibrils than contractile muscle tissue.
• Single nucleus, striated, with light and dark bands when seen through a microscope.
• The dark bands represent myosin proteins whose thickness block light passing through
The cell and appear dark.
• Between the dark bands are thin actin filaments
That allow light to pass through and appear light.
When the muscle fibers contract, myosin pulls
The actin filaments together to shrink the muscle
Skeletal striated Muscle Tissue
Origin: Mesoblasts and is innervated by the sympathetic nervous system so it can
Be controlled consciously.
• Actin and myosin work in collaboration with troponin and tropomyosin to bring
About muscular contraction.
• Symplast type of microscopic organisation
• The triad of myofibril consist of T system and 2L system.
• Long and cylindrical in shape, with nuclei located at the edges (periphery) of the
Cell, beneath the Sarcolema.
Skeletal muscle is called "striated" because of the light and dark bands visible
Under light microscope.
The dark bands represent myosin proteins whose thickness block light
Passing through the cell and appear dark.
Between the dark bands are thin actin filaments that allow light to pass
Through and appear light. When the muscle fibres contract, myosin pulls
The actin filaments together to shrink the muscle cell and make it
• Each cell is filled with sarcoplasm (specialized cytoplasm) and is surrounded by
Sarcolemma (thin cell membrane).
H- Only melanin
I bands are longer in skeletal muscle tissue than in cardiac muscle tissue
• Movement of the skeleton under
Conscious control, including
Movement of limbs, fingers, toes,